Current wireless mobile communication devices include microprocessors, memory, soundcards, and run one or more software applications in addition to providing for voice communications. Examples of software applications used in these wireless devices include micro-browsers, address books, email clients, instant messaging (“IM”) clients, and wavetable instruments. Additionally, wireless devices have access to a plurality of services via the Internet. A wireless device may, for example, be used to browse web sites on the Internet, to transmit and receive graphics, and to execute streaming audio and/or video applications. The transfer of Internet content to and from wireless device is typically facilitated by the Wireless Application Protocol (“WAP”), which integrates the Internet and other networks with wireless network platforms. Such wireless devices may operate on a cellular network, on a wireless local area network (“WLAN”), or on both of these types of networks.
With respect to WLANs, the term “Wi-Fi” (“Wireless Fidelity”) pertains to certain types of WLANs that use specifications in the Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 family. The term Wi-Fi was created by an organization called the Wi-Fi Alliance, which oversees tests that certify product interoperability. The particular specification under which a Wi-Fi network operates is called the “flavour” of the network. Wi-Fi has gained acceptance in many businesses, office buildings, agencies, schools, and homes as an alternative to a wired local area network (“LAN”). All the 802.11 specifications use the Ethernet protocol and Carrier Sense Multiple Access with Collision Avoidance (“CSMA/CA”) for path sharing. The original modulation used in 802.11 was phase-shift keying (“PSK”). However, other schemes, such as complementary code keying (“CCK”), are used in some of the newer specifications. The newer modulation methods provide higher data speed and reduced vulnerability to interference. In addition, to improve security, entities running a WLAN often use security safeguards such as encryption or a virtual private network (“VPN”).
In a WLAN, an “access point” is a station that transmits and receives data (sometimes referred to as a transceiver). An access point connects users to other users within the network and also can serve as the point of interconnection between the WLAN and a wired LAN. Each access point can serve multiple users within a defined network area. As users move beyond the range of one access point (i.e., when they roam), they are automatically handed over to the next one. A small WLAN may only require a single access point. The number of access points required increases as a function of the number of network users and the physical size of the network.
One problem with communications in a WLAN occurs when a wireless device transfers between first and second access points in the WLAN during voice calls. In particular, when a wireless device user roams around the wireless environment (e.g., a floor in an office building serviced by a WLAN) during a voice call taking place over the WLAN, the wireless connection may not necessarily be always available. For example, if the user is participating in a voice call through his/her wireless device while connected to a first access point to the WLAN and then walks across to the other side of the floor, the user's wireless device may need to transfer over to another access point to continue with the voice call. While it is possible for the transfer between access points to be seamless, there are many occasions when the WLAN coverage is not seamless and hence there will be a period of time when the user's wireless device will be without any wireless connection. Currently, this would mean that the voice call could be interrupted or abruptly dropped.
A need therefore exists for an improved method and system for transferring voice calls between access points in WLANs. Accordingly, a solution that addresses, at least in part, the above and other shortcomings is desired.
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.